This study uses a number of laboratory testing and ageing methods in order to investigate how effectively they correlate to catalyst ageing on a vehicle. The activity testing of full size catalyst bricks was successfully conducted using the Catagen Labcat test system, and correlation with the light-off activity of cored catalyst samples in the Horiba SIGU 2000 examined using the QUB global catalyst model. Static ageing was conducted in the laboratory, using the BAT equation to calculate ageing times for ageing temperatures relating to a RAT-A cycle. The thermal reactivity coefficients for static ageing in different ageing atmospheres were calculated and compared to those recommended by the EPA for dynamic ageing. Finally, using the results achieved from these raboratory ageing methods, recommendations were made as to how ageing models reviewed in the literature could be improved. From experimental results alone, it was seen that no correlation existed between the light-off performance of cored catalyst samples and full size bricks. However, the QUB global catalyst model was able to consider variations in precious metal dispersion between samples, differences between inlet temperature and gas concentrations, and heat transfer characteristics of the two reactors. The simulations performed were able to show good correlation between the test methods. However, the two tests methods showed differently the activity rank of the samples, indicating the variation in precious metal loading and dispersion throughout each full size brick. In other results, static ageing of palladium loaded catalyst samples was found to show no ageing effects due to time for ageing temperatures below 1000 C. Static ageing methods were also shown to cause deactivation at a slower rate than dynamic methods. It was shown that the Toyota ageing expression would better predict catalyst deactivation if it incorporated an oxygen factor, to describe ageing when no oxygen is present.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:695255 |
| Date | January 2015 |
| Creators | Blades, Luke Aubrey William |
| Publisher | Queen's University Belfast |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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